1. Field of the Invention
Embodiments of the present invention generally relate to a wellbore completion. More particularly, the invention relates to placing sensors in a wellbore. Still more particularly, the invention relates to placing fiber optic sensor line in a wellbore.
2. Description of the Related Art
During the past 10 years decline rates have doubled while at the same time, reservoirs are becoming more complex. Consequently, the aggressive development and installation of new technologies have become essential, such as intelligent well technology. Since downhole measurements play a critical role in the management of oil and gas reservoirs, intelligent well technology has come to the forefront. But like many new technologies, successful and reliable development of intelligent well techniques has been a challenge to design.
Prior to the introduction of permanently deployed in-well reservoir-monitoring systems, the only viable method to obtain downhole information was through the use of intervention-based logging techniques. Interventions would be conducted periodically to measure a variety of parameters, including pressure, temperature and flow. Although well logs provide valuable information, an inherently costly and risky well-intervention operation is required. As a result, wells were typically logged infrequently. The lack of timely data often compromised the ability of the operator to optimize production.
A new down-hole technology to better monitor and control production without intervention would represent a significant value to the industry. However, the challenge was to develop a cost-effective and reliable solution to integrate permanent-monitoring systems with flow control systems to deliver intelligent wells. Using a permanent monitoring system, intelligent wells have the capability to obtain a wide variety of measurements that make it easier to characterize oil and gas reservoirs. These measurements are designed to locate and track fluid fronts within the reservoir and for seismic interrogation of the rock strata within the reservoir. Additionally, intelligent completion systems are being developed to determine the types of fluids being produced prior to and after completion. Using permanent remote sensing and fiber optics, an analyzer can monitor the well's performance and production abnormalities can be detected earlier in the life cycle of the well, which can be corrected before becoming a major problem.
One challenge facing the progress of intelligent completion systems is the development of an efficient and a cost effective method of deploying fiber optic line in the wellbore. In the past several years, various deployment techniques have been developed. For example, a method for installing fiber optic line in a well is disclosed in U.S. Pat. No. 5,804,713. In this deployment technique, a conduit is wrapped around a string of production tubing prior to placing into the well. The conduit includes at least one sensor location defined by a turn in the conduit. After the string of production tubing is placed in the well, a pump is connected to an upper end of the conduit to provide a fluid to facilitate the placement of the fiber optic line in the conduit. Thereafter, the fiber optic line is introduced into the conduit and subsequently pumped through the conduit until it reaches the at least one sensor location. Using this technique for deploying fiber optic line in the wellbore presents various drawbacks. For example, a low viscosity fluid must be maintained at particular flow rate in order to locate the fiber optic line at a specific sensor location. In another example, a load is created on the fiber optic line as it is pumped through the conduit, thereby resulting in possible damage of the fiber optic line.
Another deployment technique for inserting a fiber optic line in a duct is disclosed in U.S. Pat. No. 6,116,578. In this deployment technique, a source of fiber optic line is positioned adjacent the wellbore having a pressure housing apparatus at the surface thereof. Thereafter, the fiber optic line is inserted through the pressure housing apparatus and subsequently into a tube by means of an expandable polymer foam mixture under pressure. As the polymer foam mixture expands, the foam adheres to the surface of the fiber optic line creating a viscous drag against the fiber optic line in the direction of pressure flow. The fiber optic line is subsequently urged through the duct to a predetermined location in the wellbore. Using this technique for deploying fiber optic line in the wellbore presents various drawbacks. For example, additional complex equipment, such as the pressure housing apparatus, is required to place the fiber optic line into the wellbore. In another example, the foam coating on the fiber optic line may not adequately protect the fiber optic line from mechanical forces generated during deployment into the duct, thereby resulting in possible damage of the fiber optic line. Furthermore, this deployment technique is complex and expensive.
A need therefore exists for a cost effective method of placing a fiber optic line in a wellbore. There is a further need for a method that protects the fiber optic line from damage during the deployment operation. Furthermore, there is a need for a method of placing a fiber optic line in a wellbore that does not depend on a specific flow rate or a specific viscosity fluid.